Splice Implementation

let numbers = [1, 2, 3, 4, 5, 6, 7, 8];
let startIndex = 4;
let removeCount = 3;
let addNumbers = [1, 2, 3, 4, 5];

function spliceElements(arr, start, removals, addons) {
  let modifiedArr = [];

  for (let i = 0; i < arr.length; i++) {
    let currentElement = arr[i];
    if (i === startIndex) {
      break;
    }
    modifiedArr[modifiedArr.length] = currentElement;
  }

  for (let i = 0; i < addons.length; i++) {
    let currentElement = addons[i];
    modifiedArr[modifiedArr.length] = currentElement;
  }

  for (let i = start + removals; i < arr.length; i++) {
    let currentElement = arr[i];
    modifiedArr[modifiedArr.length] = currentElement;
  }
  return modifiedArr;
}

function returnNewArray(arr, start, removals) {
  let newArr = [];

  for (let i = start; i < arr.length; i++) {
    let currentElement = arr[i];
    if (i === start + removals) {
      break;
    }
    newArr[newArr.length] = currentElement;
  }
  return newArr;
}

let spliceElementsValue = spliceElements(numbers, startIndex, removeCount, addNumbers);
console.log(spliceElementsValue);

let returnNewArrayValue = returnNewArray(numbers, startIndex, removeCount);
console.log(returnNewArrayValue);